1. Field of the Invention
The present invention relates to an electron beam control device which controls an electron beam for use, such as an electron microscope, an electron beam exposure device and the like, and in particular to an electron beam control device that overcomes the adverse influence on a track of an electron beam due to the amount of magnetic field variation occurring from surrounding influences.
2. Description of the Related Art
Control of an electron beam such as a microscope and an electron bean exposure device using an electron beam is easily Influenced by the surrounding magnetic field variation particularly in case of an electron beam exposure device for preparation of a photomask, it is known that the influence upon the positional control of an electron beam is a serious problem for increasing the semiconductor device density and the necessary miniaturization of the photomask pattern.
Recently, in an electron beam writing device with a strict positional control it is required to control the amount of magnetic field variation from 0.3 mG to 1 mG or less. There Is a need to give sufficient consideration to the environment where the device is installed.
As an installation room where such device is installed, a so-called shield room is generally provided, and the wall surface for such a shield room is made with a high magnetic field permeability material represented by Permalloy to attenuate the magnetic field variation occurring from the surrounding influence.
The method of attenuating the magnetic field variation occurring from toe surrounding influence by the above-described method, ordinarily, is called xe2x80x9ca passive magnetic shield methodxe2x80x9d.
However, to satisfy the recent-year device requirements, it is necessary to increase the number of Permalloy layers or to increase the thickness of each layer in the passive magnetic shield method. This affects the cast to rapidly rise in a cumulative basis and becomes an obstacle to decreasing the installation cost of the device.
Further, in a low-frequency range around 0.1 to 1.0 Hz, it has been confirmed that the shielding performance is degraded, and it is known that efficiently suppressing the magnetic field variation (in this range, especially) becomes difficult due to, for example, the passing-by of an automotive vehicle, etc.
In view of the above-described existing circumstances, a new type of shield room has been developed in recent years (1) to apply a magnetic coil to a figuration (ordinarily the six surfaces of a rectangular parallelepiped configuration) surrounding a space targeted for magnetic shielding, (2) to detect the magnetic field variation occurring from the surrounding influence by an internal or an external magnetometric sensor, and (3) to control the electric current flowing through the electromagnetic coil(s) so as to cancel that magnetic field variation, which actively shields the space.
The above-described method of actively attenuating the magnetic field variation occurring from the surrounding influence is called xe2x80x9can active magnetic shielding methodxe2x80x9d,
However, there still is no method with a satisfying performance enough to displace the existing shielding room, and there remains the problem that the magnetic field variation that especially comes from the neighborhood and so forth cannot be coped.
As described above, there appears to be no conventional method with sufficient performance results to displace the existing shielding room that will effectively shield the magnetic field variation that especially comes from the neighborhood. Therefore, for an electron beam control device which controls an electron beam for use, (such as an electron microscope, an electron beam exposure device and the like), a device which a track of an electron beam is not adversely influenced by the amount of magnetic field variation occurring from surrounding influences.
The present invention has been achieved In order to solve the above and other problems. It is an object of this invention to provide an electron beam control device which controls an electron beam for use (such as an electron microscope, an electron beam exposure device and the like) where a track of an electron beam is not adversely influenced by the amount of magnetic field variation occurring from surrounding influences.
In the electron beam control device of the present invention, it is an electron beam control device which controls an electron beam for use (such as an electron microscope, an electron beam exposure device and the like), where a magnetometric sensor for measuring the amount of magnetic field variation occurring from the surrounding influences, which adversely influences a track of an electron beam is provided.
Furthermore, in the above mentioned electron beam control device, a function for adjusting an electron beam control system according to the measured amount of magnetic field variation occurring from the surrounding influences is provided, where the amount of position fluctuation of an electron beam occurring due to the amount of magnetic field variation is calculated and a position of an electron beam is corrected to a position where the amount of position fluctuation is cancelled.
Still more, In the above mentioned electron beam control device, a function for displaying such fact and/or stopping an electron beam manipulation, when the measured amount of magnetic field variation occurring from the surrounding influences exceeds a predetermined range, is provided.
The electron beam control system here includes the meaning of an electron-optical system portion.
The electron beam control system of the present invention, by having the above-described construction, has enabled to provide an electron beam control device, such as an electron microscope and an electron beam exposure device, where a track of an electron beam is not adversely influenced by the amount of magnetic field variation occurring from surrounding influences.
A magnetometric sensor for measuring the amount of magnetic field variation is provided in the electron beam control device to stop the electron beam manipulation, or to correct the position of the electron beam by adjusting the control system, according to the measured amount of magnetic field variation. Thereby, it enables to control the influence of the magnetic field variation.
By this, it is possible to control the positional variation of the electron beam due to the magnetic field variation and to realize the electron beam position control with a high accuracy.
The present invention, as described above, provides an electron beam control device which controls an electron beam for use, (such as an electron microscope, an electron beam exposure device and the like) where a track of an electron beam is not adversely influenced by the amount of magnetic field variation occurring from surrounding influences.
That is to say, it is possible to realize a high accuracy electron beam control from device that is not influenced of the amount of magnetic field variation occurring from the surrounding influences.
As a result of this, especially in the electron beam exposure device for use for the preparation of a photomask under technological requirements in recent years to increase in the density of the semiconductor device and to miniaturize the pattern of the photomask, effectively shielding the influence of the amount of magnetic field variation occurring from the surrounding influences has been desired for the quality of the product, among others.